Acute interstitial nephritis with prominent eosinophil infiltration

Aims: Acute interstitial nephritis (AIN) is common, but prominent eosinophil infiltration in patients with acute interstitial nephritis is rare. The possible etiologies, predisposing factors and treatment of such patients are the subjects of this study. Methods: one patient was reported from our medical center; nine more patients with similar findings were reviewed from the literature. Suspected offending drugs, clinical presentations, predisposing factors and patient outcomes after therapy were recorded. Results: A case of clam extract-associated acute interstitial nephritis with prominent eosinophil infiltration was reported. Ten cases including ours were analyzed. A variety of drugs was thought to be causative. In all, 7 of the 10 patients had a preexisting nephrotic syndrome, and eosinophilia was found in 6. Bone marrow biopsy was not performed in most cases and only available for 2 patients including ours. 9 patients treated with steroids had good responses but 1 patient died despite treatment. Conclusions: Acute interstitial nephritis with prominent eosinophil infiltration can be caused by a great diversity of drugs, which can include clam extract tablets. A preexisting nephrotic syndrome seemed to be a predisposing factor for this condition. This disease rarely led to fatality and most patients responded well to steroid therapy.